The disclosure of Japanese Patent Application No. 2001-88422 filed on Mar. 26, 2001 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
1. Field of Invention
The invention relates to an intake control apparatus and methods of an internal combustion engine that has an intake control valve in an intake pipe downstream of a throttle valve.
2. Description of Related Art
In a known technology, smaller particles of injected fuel during startup of an engine are formed to achieve a stable combustion by controlling the air current in an intake pipe. The air current is controlled through the use of an intake control valve disposed in the intake pipe and downstream of a throttle valve. Furthermore, by forming turbulences in the air current in cylinders of the engine, lean combustion is made possible which improves the exhaust emission quality.
An example of the aforementioned technology is described in Japanese Patent Application Laid-Open No. 4-191433. This patent application describes a process for detecting and determining a combustion property based on the combustion in an engine. The technology improves combustion by restricting the closing action of the intake control valve, until a property of fuel has been detected and determined. Furthermore, the detection and determination of the property of fuel is performed with high precision, thus ensuring good vehicle running performance.
However, if deterioration of the combustion occurs, for example, the property of fuel is inferior, then restriction of the closing action of the intake control valve can occur, which results in a reduction or elimination of the combustion performance improving effect. Accordingly, this reduction or elimination can degrade the state of the operation of the engine, thus discomforting an occupant in the vehicle. Furthermore, when the restriction of the closing action of the intake control valve is prevented, or when an opening action of the valve is caused, the state of the combustion in the engine changes which can cause produced torque to fluctuate depending on conditions, and therefore an occupant may be discomforted.
Accordingly, it is an object of the invention to provide an intake control apparatus and methods of an internal combustion engine that reduce the discomfort caused to a vehicle occupant by the changes in the combustion in the engine, even during the opening and closing actions of an intake control valve.
In accordance with a first aspect of the invention, an intake control apparatus of an internal combustion engine includes an intake control valve disposed in an intake pipe downstream of a throttle valve. The control apparatus and methods control an opening and closing of the intake control valve based on a stability of the combustion in the internal combustion engine during a period from a start-up to a warm-up of the internal combustion engine.
Therefore, by controlling the intake control valve based on the stability of the combustion, deterioration in the operation of the engine can be reduced or prevented, thus also reducing the discomfort caused to a vehicle occupant.
In accordance with a second aspect of the invention, an intake control apparatus and methods of an internal combustion engine includes an intake control valve disposed in an intake pipe downstream of a throttle valve. The control apparatus and methods change an open-closed state of the intake control valve during a period from a start-up to a warm-up of the internal combustion engine, and determine a property of a fuel based on a change in the operation of the internal combustion engine that is caused by the changing of the open-closed state of the intake control valve.
Since the state of the combustion can be changed by the open-close control of the intake control valve, it becomes possible to determine the property of the fuel with high precision by actively performing the open-close control to intentionally change the combustion, and by measuring changes in the operation of the engine that occur in association with the changes in the combustion.
In accordance with a third aspect of the invention, an intake control apparatus and methods of an internal combustion engine include an intake control valve disposed in an intake pipe downstream of a throttle valve. The control apparatus and methods control an opening and closing of the intake control valve synchronously with a change in a load on the internal combustion engine.
Therefore, if the open-close control of the intake control valve changes the combustion so that the state of output of the internal combustion engine fluctuates, such fluctuations are absorbed or offset by fluctuations in the load. Since fluctuations in the load can be anticipated by vehicle occupants, fluctuations in the load will not considerably dismay or discomfort vehicle occupants.
In accordance with a fourth aspect of the invention, an intake control apparatus and methods of an internal combustion engine includes an intake control valve disposed in an intake pipe downstream of a throttle valve. The control apparatus and methods control the intake control valve to close the intake control valve upon determining that the property of the fuel being used is inferior.
Therefore, if it is determined that the property of the fuel is inferior, that is, if it is determined that the property of the fuel will prevent a certain stability of combustion from being maintained if the intake control valve is opened, the intake control valve is maintained closed in order to improve combustion, and maintain a predetermined stability of combustion.
The invention is not limited to the intake control apparatuses and methods of the first to fourth aspects, but is also applicable to vehicles equipped with an intake control apparatus as described above, and to a control method thereof.